/**
    1. 已知小明nodejs成绩?根据成绩求成绩等级(90-100 A级, 80-89 B级,  70-79 C级, 60-69 D级, 其它为不合格  )

        100 / 10    -> 10
        90-99 / 10  -> 9
        80-89 / 10  -> 8
        70-79 / 10  -> 7
        60-69 / 10  -> 6
 */

var score = 85  // 小明nodejs成绩
var gradeScore = parseInt(score/10) 

switch(gradeScore){
    case 10:
    case 9:
        console.log("A");
        break;
    case 8:
        console.log("B");
        break;
    case 7:
        console.log("C");
        break;
    case 6:
        console.log("D");
        break;
    default:
        console.log("不合格")
}